ul, li {
    list-style-type: none;
}
ul, ol {
    margin: 0;
    padding: 0;
}
.lf {
    float: left;
    border: 0px solid #000;
}
.nav-ul {
    display: -webkit-flex; /* Safari */
    display: flex;
    justify-content: space-between;
    flex-wrap: nowrap;
    flex-direction: row;
}
.nav-ul > li {
    display: inline-block;
    cursor: pointer;
    box-sizing: border-box;
    font-size: 0.12rem;
    height: 20px;
    position: relative;
    background-color: #fff;
    transition: 0.1s all linear;
    padding: 2px 5px 0 5px;
}
.nav-ul > li::before {
    position: absolute;
    content: '';
    left: 100%;
    top: 0;
    width: 0;
    height: 100%;
    border-bottom: 2px solid #000;
    transition: 0.2s all linear;
}
.nav-ul > li:hover::before {
    width: 100%;
    left: 0;
}
.nav-ul > li:hover ~ li::before {
    left: 0;
}
.nav-ul > li:active {
    background-color: #000;
    color: #fff;
}

